Winches of many different configurations are known. For use in vehicles, for example to assist a vehicle which has become bogged or for emergency service vehicles, winches are mounted on or adjacent the forward bumper or bull bar and have ranged from the older style capstan winches having a vertical spool, to power takeoff winches and hydraulic winches run off the vehicle gearbox. More recently, electric winches which have an electric motor driven from the vehicle battery have become a preferred winch for use on vehicles. Another form of known winch is an hydraulic winch which uses the vehicles own power steering fluid as the source of fluid to drive the hydraulic motor of the winch.
A major disadvantage of the common electric winches is that the current drain on the vehicle battery can be very high during winch operation. For example, electric winches can draw a current in the order of 500 amps which obviously places a considerable load on a normal vehicle battery which may be only rated at 70 amp/hour. As a result the known electrical winches can only be used for a short period of time before the vehicle battery becomes completely drained. A further disadvantage of electric winches is that they cannot operate underwater or in mud.
The known hydraulic winches also suffer a number of disadvantages in that they tend to require a large quantity of hydraulic fluid for their operation and furthermore they tend to heat up rapidly when subject to a load. They also have limited line speed.